1. Field of the Invention
The present invention relates, in general, to the transmission of fluids or electromagnetic waves. More particularly, the present invention relates to an apparatus for the smooth bending of a flexible conduit, such as a waveguide.
2. Discussion of the Related Art
It is well known that the propagation of electromagnetic waves can be guided through the application of conducting or metallic boundaries. If the frequency of an electromagnetic wave is high enough that the wavelength is comparable to the cross-sectional dimensions of the boundaries, then transmission between the boundaries becomes well defined. With uniform (non-tapered) boundaries, the voltage or current applied at the sending end of the boundaries determines the shape of the initial voltage or current wave. With boundaries having negligible losses, the transmitted shape remains unchanged.
Various devices have been employed in order to constrain or guide the propagation of electromagnetic waves along a path defined by the physical construction of the device. These devices include coaxial transmission lines and strip lines. Coaxial transmission lines consist of a dielectric material bounded by two coaxial, cylindrical conducting walls. Strip lines are constructed with a metal strip above a metal plane or with a metal strip between two metal planes. In either case, a dielectric material is used to insulate the metal strip and the ground plane or planes.
It is also known that the propagation of electromagnetic waves can be guided by using a waveguide. In a broad sense, devices such as coaxial transmission lines can be categorized as waveguides. However, in a more restricted sense and that used herein, the term waveguide refers to a metallic tube adapted to confine and guide the propagation of electromagnetic waves in the hollow space along the longitudinal direction of the tube. Hollow waveguides of convenient sizes are readily adapted to the transmission of microwaves.
While prior devices for guiding the transmission of electromagnetic waves have generally proven effective, they also have been associated with several disadvantages. For example, flexible waveguides are often used in microwave systems where rotation of part of the system with respect to the remainder of the system is required. An example of a system in which rotation would be desirable is a transmitter wherein it is necessary to guide electromagnetic waves between the transmitter and a rotatable antenna.
Simple rotation of one end of a flexible waveguide with respect to the other end using a fixed axis of rotation causes the effective length of the waveguide to become compressed. This compression often causes the waveguide to buckle. When buckling occurs, the stresses and strains involved can be expected to be higher than that encountered in simple bending. Such higher stresses and strains often lead to premature failure where the flexible waveguide is subject to repeated cycling.
Furthermore, buckling tends to change the effective length of the waveguide and often leads to undesired phase shifting of the transmitted electromagnetic waves. The greater the angle of rotation, the greater change in the effective length of the waveguide.
Thus, it is highly desirable to provide an apparatus which minimizes buckling of a flexible waveguide throughout rotation. That is, it is highly desirable to provide an apparatus for smooth bending of a flexible waveguide. Simple, uniform bending of a flexible waveguide provides a uniform level of stress and strain, at an optimal, minimized level. Further, as many flexible waveguides are designed to be cycled repeatedly during operation, reduced stress and strain levels can be expected to significantly increase component life and thereby decrease maintenance and replacement.